Songwriters Bobby Lopez and Kristen Anderson-Lopez spent two years working on the music and lyrics to “Frozen,” the new Disney animated musical about a wintry kingdom opening today.

Having grown up “with a steady diet of Disney,” the husband-and-wife team studied the films “The Little Mermaid,” “Beauty and the Beast,” and “Aladdin” — all by lyricist Howard Ashman and composer Alan Menken.

“We are huge fans of everyone who has come before us and now that we’ve been through this journey – we bumped into Menken at a party the other day and I was like, I can’t believe you did so many of them,” Kristen says. “They’re so hard, and you have to really check your ego at the door.”

The Lopezes say there are more than 20 songs that ended up on the cutting room floor — but here, they discuss four of the “Frozen” songs that didn’t. (Warning, there are some spoiler details about the film “Frozen.”)

“Do You Want to Build a Snowman?”: Performed by Kristen Bell, Agatha Lee Monn and Katie Lopez (Bobby and Kristen’s eight-year-old daughter).

“Do You Want to Be a Snowman” was inspired by a storyboard image of two young sisters, Princess Anna and her older sister, Queen Elsa. As young girls, Anna often spent her days knocking on Elsa’s door, asking her out to play. “We were having a really hard time figuring out what the front of this movie needed to sound like and do,” Kristen says. “I saw this image of the two of them on either side of the door and I said, ‘That’s our song. It’s about knocking on the door over and over again and never having anybody answer.’”

For a couple bars in the song, young Anna sings through the keyhole to Elsa. The way the animation and voice came together in that scene illustrates how the Lopezes worked daily with “Frozen” directors Chris Buck and Jennifer Lee on the visualization of their music. “We had written the song and recorded it. They said when you get a chance, have your daughter cup her hands to her mouth as she sings that line. We want her to sing that line through the keyhole,” Bobby says. “It’s so funny, the process of chicken and egg that you go through with these things. One side inspires the other, inspires the other back, and inspires the other back — and hopefully the whole thing gets better.”

“For the First Time In Forever”: Performed by Kristen Bell and Idina Menzel.

This number encapsulates the sisters’ two different points-of-view on life in the kingdom of Arendelle. The songwriters wanted to introduce the optimistic side to Anna, but with an element of sadness and isolation underlying it since she’s been knocking on Elsa’s door. Meanwhile, Elsa has kept her secret, somewhat dangerous powers behind that door in order to protect herself and Anna. “When we finally realized they would both have very different points-of-view about the door opening and letting people in, we found our song,” Kristen says.

In the scene, as the two sisters’ perspectives become clear, Bell and Menzel sing back and forth in quick succession, a technique called hocketing. “I know that works on stage, but you haven’t necessarily seen it in movies all that much,” Bobby says. “It wasn’t a given it would work.” But he says that moment turned out to be very cinematic and evidence of “what musical storytelling does best — showing two different characters singing completely opposite points-of-view about the same thing, and then having this wonderful clash in a musical way.”

“Let It Go”: Performed by Idina Menzel in the film; single release performed by Demi Lovato.

The movie’s showstopper, “Let It Go,” was written for Idina Menzel (“Rent,” “Wicked”), whom Bobby calls “one of the most glorious voices of Broadway and an icon in musical theater.” He says the song emerged from the singer’s palette — “the low, vulnerable, fragile side of her low end, and then the power that’s inherent in her belt range.” When Disney heard the song, they suggested releasing it as a single. The Lopezes had narrowed the list of potential singers down to three, with Lovato at the top. “It just so happened that Demi was part of the Disney family already, and that she had a past that she’s pretty open about that is similar to Elsa’s journey of letting a dark past and fear behind and moving forward with your power,” Kristen says.

“In Summer”: Performed by Josh Gad.

From the moment Olaf the snowman says “Nope!” (when asked if he’s had much experience with heat), this song feels like a little film within the film. Olaf naively envisions a happy life as a snowman in the sun. (“A drink in my hand, my snow up against the burning sand, probably getting gorgeously tanned — in summer!”) Gad played the role of Elder Cunningham in Broadway’s “The Book of Mormon” (which Bobby co-wrote). “We in our heart of hearts really wanted to write ["In Summer"] for Josh,” Bobby says. “We knew Josh’s best high notes, we knew what Josh is really good at. I like to think we tailor-fitted it for him and he knocked it out of the park.” Kristen adds that her husband does an excellent impression of Gad, saying “If you can’t afford Josh Gad, you can afford Bobby Lopez’s Josh Gad.”